In recent years, lithium secondary batteries have grown increasingly important as on-board vehicle power supplies and power supplies for personal computers and handheld devices. In particular, it is expected that lithium ion secondary batteries, which are lightweight and capable of achieving a high energy density, will see preferred use as high-output power supplies for on-board use in vehicles. In one typical lithium ion secondary battery configuration, charging and discharging are carried out by the movement of lithium ions back and forth between a positive electrode mixture layer containing a positive electrode active material and a negative electrode mixture layer containing a negative electrode active material. The negative electrode active material is preferably a carbon material having in at least a portion thereof a graphite structure. Examples of technical literature relating to lithium secondary batteries include Patent Documents 1 to 4.    Patent Document 1: Japanese Patent Application Laid-open No. H5-41251    Patent Document 2: Japanese Patent Application Laid-open No. 2006-303118    Patent Document 3: Japanese Patent Application Laid-open No. 2002-110250    Patent Document 4: Japanese Patent Application Laid-open No. H6-338345
It is expected that, of the various applications for lithium ion secondary batteries, there may be some in which the battery is placed under broad temperature conditions ranging from low to high temperature and used in a manner where it is repeatedly charged at a high rate (quick charging). Lithium ion secondary batteries to be used as the power source in vehicles (e.g., lithium ion secondary batteries mounted in hybrid vehicles which use both lithium ion secondary batteries and another source of power having a different principle of operation, such as an internal combustion engine) are illustrative of lithium ion secondary batteries for which such a manner of use is anticipated. There exists a desire that lithium ion secondary batteries for such applications, on exposure to the above broad temperature range conditions, incur little decrease in capacity (have a high capacity retention) even when placed in a state of non-use for an extended period of time, and experience little decrease in battery performance even when repeatedly charged at a high rate (e.g., undergo little rise in internal resistance).
However, because capacity retention and high-rate characteristics are generally contradictory properties, achieving both these properties to a high level at the same time is difficult. In light of these circumstances, the chief object of the present invention is to provide a lithium ion secondary battery which exhibits a high capacity retention even when stored under high-temperature conditions, and which undergoes little deterioration in performance even when a charge-discharge pattern that includes high-rate charging is repeated under low-temperature conditions.